This lecture defines and gives examples of phase, one phase and two phase systems, equilibrium, component, and triple point. A detailed discussion of the most familiar one phase system, water, is followed by comparisons of the phase diagrams of aluminum and silicon.

Prof. Sadoway does some live demonstrations for the class:

various objects are immersed in liquid nitrogen, going below their glass transition temperature

properties of liquid oxygen

sublimation of solid frozen CO2, aka 'dry ice'

The phase diagram of zirconia illustrates the concept of changing a material's composition to produce desired behaviors at particular temperature/pressure conditions. The phase diagram of carbon illustrates how artificial diamonds are made. Bisumth and sulfur phase diagrams – "phase diagrams from hell" – have many regions. Returning to water, Prof. Sadoway discusses the unusual phases of ice at very high pressures and very low temperatures.

As a final application note, the lecture ends with a quick summary of coffee decaffeination as a process employing sophisticated manipulation of phase transitions.

About MIT OpenCourseWare

MIT OpenCourseWare makes the materials used in the teaching of almost all of MIT's subjects available on the Web, free of charge. With more than 2,400 courses available, OCW is delivering on the promise of open sharing of knowledge. Learn more »